If you've ever looked outside, seen blue skies and wondered why your flight is delayed, wildfire smoke could be the reason.

Smoke doesn't just make the air hazy. It can disrupt air travel in several ways, from reducing visibility for pilots to forcing airspace closures so firefighting aircraft can safely battle nearby blazes.

In fact, the FAA says wildfire smoke can be more likely to cause flight delays than rain or fog. This is because smoke, unlike water droplets, is made up of tiny solid particles that linger in the atmosphere and can interfere with navigation.

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(MORE: How summer weather causes flight delays)

What passengers need to know

For travelers, that means delays. Smoke from wildfires can travel hundreds of miles, creating poor visibility at airports far from the flames.

"Thick smoke reduces visibility at airports, forcing air traffic control to space planes further apart and slowing down the rate of takeoffs and landings," explains Richard Adams, a senior manager of forecast operations for The Weather Company.

The time of day also matters. A pilot landing into a low sun shining through a layer of smoke may have little to no visibility. Airports with east-west runways are especially vulnerable.

(MORE: How the biggest wildfires can change the weather)

The most intense wildfires can also create their own weather.

"Intense heat from wildfires creates strong, unpredictable updrafts of hot air that can cause significant turbulence for aircraft flying above," says Adams. "Though this tends to be constrained to the lower half of the atmosphere rather than at cruise altitude."

The good news? The air inside the cabin is generally not the concern.

"Commercial aircraft use high-efficiency HEPA filters that safely remove over 99.9% of smoke particles from the cabin air, though a faint campfire smell might still linger," Adams says.

(MORE: Planes scoop the Seine to battle wildfire in France)

What about pilots?

Pilots face additional challenges. Firefighting aircraft like air tankers, helicopters and lead planes often operate at low altitudes in smoky conditions, making it critical for other aircraft to stay clear of active fire zones.

Prolonged exposure to dense smoke can also wear on engines, clogging filters and affecting sensitive pressure systems.

As wildfire seasons grow longer and more intense, smoke is becoming more than just an air quality issue; It's increasingly becoming a major factor in keeping air travel moving safely.